C#实现文件上传与下载功能实例

最近学习了 C#实现文件上传与下载，现在分享给大家。

1、C#文件上传

创建MyUpload.htm页面，用于测试

<form name="form1" method="post" action="UploadFile.aspx" id="form1"  
enctype="multipart/form-data">
 <input type="file" id="txtFile" name="picfile" /></br>
 <input type="submit" value="上传" />
</form>

创建UploadFile.aspx文件，在UploadFile.aspx.cs键入如下代码：

Random rnd = new Random();              //产生随机数
private string _directory = @"/File/UploadFile";   //目录
protected void Page_Load(object sender, EventArgs e)
{
 try
 {
   if (RequestFilesCount > 0)
   {
     //判断文件大小
     int length = RequestFiles[0]ContentLength;
     if (length > 1048576)
     {
       ResponseWrite("文件大于1M，不能上传");
       return;
     }

string type = RequestFiles[0]ContentType;
     string fileExt = PathGetExtension(RequestFiles[0]FileName)ToLower();
     //只能上传图片，过滤不可上传的文件类型
     string fileFilt = "gif|jpg|php|jsp|jpeg|png|";
     if (fileFiltIndexOf(fileExt) <= -1)
     {
       ResponseWrite("对不起！请上传图片！！");
       return;
     }
     else
     {
       string fileName = ServerMapPath(_directory) + "\\" + DateTimeNowToString("yyyyMMddHHmmssfff") + rndNext(10, 99)ToString() + fileExt;
       RequestFiles[0]SaveAs(fileName);
       ResponseWrite("上传成功！");
     }
   }
 }
 catch
 {
   throw new Exception();
 }
}

2 、C#文件下载

创建DownloadFile.aspx，在DownloadFile.aspx.cs键入如下方法：

/// <summary>
/// C#文件下载
/// </summary>
/// <param name="filename"></param>
public void MyDownload(string filename)
{

string path = ServerMapPath("/File/"+filename);
 if(!FileExists(path))
 {
   ResponseWrite("对不起！文件不存在！！");
   return;
 }
 SystemIOFileInfo file = new SystemIOFileInfo(path);
 string fileFilt="asp|aspx|php|jsp|ascx|config|asa|"; //不可下载的文件，务必要过滤干净
 string fileName = fileName;
 string fileExt = fileNameSubstring(filenameLastIndexOf(""))Trim()ToLower();
 if(fileFiltIndexOf(fileExt)!=-1)
 {
   ResponseWrite("对不起！该类文件禁止下载！！");
 }
 else
 {
   ResponseClear();
   ResponseAddHeader("Content-Disposition", "attachment; filename=" + HttpUtilityUrlEncode(fileName));
   ResponseAddHeader("Content-Length", fileLengthToString());
   ResponseContentType = GetContentType(HttpUtilityUrlEncode(fileExt));
   ResponseWriteFile(fileFullName);
   ResponseEnd();
 }
}

/// <summary>
/// 获取下载类型
/// </summary>
/// <param name="fileExt"></param>
/// <returns></returns>
public string GetContentType(string fileExt)
{
 string ContentType;
 switch (fileExt)
 {
   case "asf":
     ContentType = "video/x-ms-asf"; break;
   case "avi":
     ContentType = "video/avi"; break;
   case "doc":
     ContentType = "application/msword"; break;
   case "zip":
     ContentType = "application/zip"; break;
   case "xls":
     ContentType = "application/vndms-excel"; break;
   case "gif":
     ContentType = "image/gif"; break;
   case "jpg":
     ContentType = "image/jpeg"; break;
   case "jpeg":
     ContentType = "image/jpeg"; break;
   case "wav":
     ContentType = "audio/wav"; break;
   case "mp3":
     ContentType = "audio/mpeg3"; break;
   case "mpg":
     ContentType = "video/mpeg"; break;
   case "mepg":
     ContentType = "video/mpeg"; break;
   case "rtf":
     ContentType = "application/rtf"; break;
   case "html":
     ContentType = "text/html"; break;
   case "htm":
     ContentType = "text/html"; break;
   case "txt":
     ContentType = "text/plain"; break;
   default:
     ContentType = "application/octet-stream";
     break;
 }
 return ContentType;
}

*如何获取现有文件的ContentType属性

/// <summary>
/// 获取现有文件的ContentType属性
/// </summary>
/// <param name="filename"></param>
/// <returns></returns>
public string GetFileContentType(string filename)
{
 string[] array = filenameSplit('');
 string result = stringEmpty;
 string suffix = "" + array[arrayLength - 1];
 MicrosoftWinRegistryKey rg = MicrosoftWinRegistryClassesRootOpenSubKey(suffix);
 object obj = rgGetValue("Content Type");
 result = obj != null ? objToString() : stringEmpty;
 rgClose();
 return result;
}

来源：http://blog.csdn.net/pan_junbiao/article/details/7185382